Turn them off
Originally Posted by Dork Knight
although you would need to replace the caps after X amount of time.
The X in my case with regards to the NAIM was 10 years
NAIM must be part of the space program... 10 years is over 87,000 hours.
That's a tremendous reliability landmark for any component - especially those in the power supply...
Failures may not have a puff of smoke attached to them. Sound can degrade slowly and you'd think that all is OK. Just check leaks on coupling caps in your average vintage tube gear...
My recommendation is to turn off any electronic component if you're not using it in the next 2-3 hours. Leave it on otherwise. Most units are not sensitive to power-on current surge, so forget that myth. Most components do need 30 minutes to an hour for warm-up, but that doesn't mean it has to be on over night because you want to listen to it the next day when you come back from work...
You'll be doing yourself a favor and save the environment at the same time. That's two birds in one shot - how can you go wrong?!